Morpholine-substituted poly(arylene ether) and method for the preparation thereof

ABSTRACT

A poly(2,6-dimethyl-1,4-phenylene ether) prepared using a morpholine-containing polymerization catalyst has a monomodal molecular weight distribution with a reduced content of very high molecular weight species. It also exhibits increased morpholine incorporation in the high molecular weight fraction. Compared to commercially available poly(2,6-dimethyl-1,4-phenylene ether) prepared using a di-n-butylamine-containing polymerization catalyst, the poly(2,6-dimethyl-1,4-phenylene ether) of the invention exhibits reduced odor. Compared to other poly(2,6-dimethyl-1,4-phenylene ether) prepared using a morpholine-containing polymerization catalyst, the poly(2,6-dimethyl-1,4-phenylene ether) of the invention exhibits improved molecular weight build during compounding and improved compatibilization with polyamides.

BACKGROUND OF THE INVENTION

Poly(arylene ether) resins are a class of plastics known for excellentwater resistance, dimensional stability, and inherent flame retardancy,as well as high oxygen permeability and oxygen/nitrogen selectivity.Properties such as strength, stiffness, chemical resistance, and heatresistance can be tailored by blending poly(arylene ether) resins withvarious other plastics in order to meet the requirements of a widevariety of consumer products, for example, plumbing fixtures, electricalboxes, automotive parts, and insulation for wire and cable. Thepoly(arylene ether) most commonly used and widely commercially availableis poly(2,6-dimethyl-1,4-phenylene ether).

Various odorous impurities that may be present in poly(arylene ether)resins have discouraged its adoption for odor-sensitive applicationssuch as the molding of containers for food, cosmetics, andpharmaceuticals. One source of odors in poly(arylene ether) resins isdi-n-butylamine, which is used as a component of the polymerizationcatalyst employed by the two largest manufacturers ofpoly(2,6-dimethyl-1,4-phenylene ether). The resultingpoly(2,6-dimethyl-1,4-phenylene ether) resins can exhibit adi-n-butylamine-related odor from free di-n-butylamine impurities in thepoly(2,6-dimethyl-1,4-phenylene ether). On the other hand,di-n-butylamine is also incorporated into thepoly(2,6-dimethyl-1,4-phenylene ether) molecule as di-n-butylaminosubstituents, the thermal decomposition of which can provide abeneficial increase in poly(2,6-dimethyl-1,4-phenylene ether) molecularweight during compounding, as well as improved compatibilization ofpoly(2,6-dimethyl-1,4-phenylene ether) with incompatible resins such aspolyamides.

One approach to reducing the odor of poly(2,6-dimethyl-1,4-phenyleneether) resins has been to utilize polymerization catalysts with lessodorous amines. For example, proton nuclear magnetic resonancespectroscopy (¹H NMR) analysis of a poly(2,6-dimethyl-1,4-phenyleneether) obtained in China from Bluestar New Chemical Materials Co.,Ruicheng Branch, China, indicates the presence of morpholinosubstituents and the absence of di-n-butylamino substituents. Thisanalysis suggests that these poly(2,6-dimethyl-1,4-phenylene ether)resins are synthesized using a polymerization catalyst comprisingmorpholine rather than di-n-butylamine. Although thepoly(2,6-dimethyl-1,4-phenylene ether) resins synthesized with amorpholine-containing catalyst exhibit reduced odor, they also exhibitundesirable reductions in their molecular weight increase duringcompounding and their compatibilization with resins such as polyamides.Thus, there remains a need for a poly(2,6-dimethyl-1,4-phenylene ether)which is synthesized without di-n-butylamine but which exhibits themolecular weight gain and compatibilization advantages ofpoly(2,6-dimethyl-1,4-phenylene ether) resins synthesized withdi-n-butylamine.

BRIEF DESCRIPTION OF THE INVENTION

The above-described drawbacks are alleviated by apoly(2,6-dimethyl-1,4-phenylene ether), wherein a purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether) prepared by dissolution of thepoly(2,6-dimethyl-1,4-phenylene ether) in toluene, precipitation frommethanol, reslurry, and isolation has a monomodal molecular weightdistribution in the molecular weight range of 250 to 1,000,000 atomicmass units, and comprises less than or equal to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times the number average molecular weight of the entirepurified sample; wherein the purified sample after separation into sixequal poly(2,6-dimethyl-1,4-phenylene ether) weight fractions ofdecreasing molecular weight comprises a first, highest molecular weightfraction; and wherein the first, highest molecular weight fractioncomprises at least 10 mole percent of poly(2,6-dimethyl-1,4-phenyleneether) comprising a terminal morpholine-substituted phenoxy group.

This and other embodiments are described in detail below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plot of the molecular weight distribution for a purifiedsample of the poly(2,6-dimethyl-1,4-phenylene ether) prepared accordingto Example 2.

FIG. 2 is a plot of the molecular weight distribution for a purifiedsample of a commercially obtained poly(2,6-dimethyl-1,4-phenylene ether)solid powder designated Comparative Example 4.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have conducted research directed to the productionof poly(2,6-dimethyl-1,4-phenylene ether) having reduced odor comparedto such polymers synthesized using a dibutylamine-containing catalyst,but retaining the desirable physical and rheological properties of suchpolymers. Reduced odor was exhibited by apoly(2,6-dimethyl-1,4-phenylene ether) obtained in China from acommercial supplier and apparently synthesized withmorpholine-containing catalyst (as indicated by proton nuclear magneticresonance spectroscopy (¹H NMR)). However, thispoly(2,6-dimethyl-1,4-phenylene ether) exhibited inferior extrusionproperties and undesirably reduced molecular weight increase duringcompounding. It also exhibited an undesirably reduced ability to formcompatibilized blends with polyamides. In their research, the presentinventors have prepared a poly(2,6-dimethyl-1,4-phenylene ether) thatexhibits desirable odor reduction while reducing or eliminating theundesirable physical, chemical, and rheological properties associatedwith known poly(2,6-dimethyl-1,4-phenylene ether) resins prepared with amorpholine-containing catalyst. Specifically, a purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether) prepared by dissolution of thepoly(2,6-dimethyl-1,4-phenylene ether) in toluene, precipitation frommethanol, reslurry, and isolation, all as described in the workingexamples below, has a monomodal molecular weight distribution in themolecular weight range of 250 to 1,000,000 atomic mass units, andcomprises less than or equal to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times the number average molecular weight of the entirepurified sample (i.e., the purified sample as a whole). The presentpoly(2,6-dimethyl-1,4-phenylene ether) also exhibits increasedmorpholine incorporation into its high molecular weight polymer chains.Specifically, the purified sample of the presentpoly(2,6-dimethyl-1,4-phenylene ether), after separation into sixfractions of equal poly(2,6-dimethyl-1,4-phenylene ether) weight contentand decreasing molecular weight (as described in the working examples),comprises a first, highest molecular weight fraction comprising at least10 mole percent of poly(2,6-dimethyl-1,4-phenylene ether) comprising aterminal morpholine-substituted phenoxy group. In other words, at least10 percent of the molecules in the first, highest molecular weightfraction comprise a terminal morpholine-substituted phenoxy group.

Compared to known poly(2,6-dimethyl-1,4-phenylene ether) resins preparedwith a morpholine-containing catalyst, the presentpoly(2,6-dimethyl-1,4-phenylene ether) exhibits reduced content of veryhigh molecular weight species. This difference has practicalsignificance because a high content of very high molecular weightspecies has been correlated with diminished performance in extrusionapplications. The reduced content of very high molecular weight speciescan be objectively quantified in various ways. For example, as notedabove, a purified sample prepared from the presentpoly(2,6-dimethyl-1,4-phenylene ether, comprises less than or equal to2.2 weight percent of poly(2,6-dimethyl-1,4-phenylene ether) having amolecular weight more than fifteen times the number average molecularweight of the entire purified sample. In some embodiments, the purifiedsample comprises 0.1 to 2.2 weight percent, specifically 0.2 to 2 weightpercent, of poly(2,6-dimethyl-1,4-phenylene ether) having a molecularweight more than fifteen times greater than the number average molecularweight of the entire purified sample. In some embodiments, the purifiedsample comprises less or equal to than 2.4 weight percent, specifically0.5 to 2.4 weight percent, of poly(2,6-dimethyl-1,4-phenylene ether)having a molecular weight greater than seven times the peak molecularweight of the entire purified sample. In some embodiments, the purifiedsample comprises less than or equal to 3.2 weight percent, specifically2 to 3.2 weight percent, of poly(2,6-dimethyl-1,4-phenylene ether)having a molecular weight greater than five times the peak molecularweight of the entire purified sample. As used herein, the term “peakmolecular weight” is defined as the most commonly occurring molecularweight in the molecular weight distribution. In statistical terms, thepeak molecular weight is the mode of the molecular weight distribution.In practical terms, when the molecular weight is determined by achromatographic method such as gel permeation chromatography, the peakmolecular weight is the poly(2,6-dimethyl-1,4-phenylene ether) molecularweight of the highest point in a plot of molecular weight on the x-axisversus absorbance on the y-axis. A detailed procedure for determining amolecular weight distribution using gel permeation chromatography ispresented in the working examples.

Compared to known poly(2,6-dimethyl-1,4-phenylene ether) resins preparedwith a morpholine-containing catalyst, the presentpoly(2,6-dimethyl-1,4-phenylene ether) exhibits increased morpholineincorporation into the high molecular weight species. This differencehas practical significance because increased morpholine incorporation,and especially increased morpholine incorporation in the terminalposition, has been observed to correlate with increased molecular weightbuild during compounding and improved compatibilization with polyamides.The increased morpholine incorporation can be objectively quantified invarious ways. For example, as noted above, when the purified sample isseparated into six fractions of equal poly(2,6-dimethyl-1,4-phenyleneether) weight content and decreasing molecular weight, the first,highest molecular weight fraction comprises at least ten mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group. In other words, within theone-sixth of the purified sample molecular weight distribution havingthe highest molecular weight, at least ten mole percent of thepoly(2,6-dimethyl-1,4-phenylene ether) comprises a terminalmorpholine-substituted phenoxy group. In some embodiments, the first,highest molecular weight fraction comprises 10 to 40 mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group.

Another advantage of the present poly(2,6-dimethyl-1,4-phenylene ether)is that it incorporates terminal morpholine residues more uniformly intoboth low and high molecular weight poly(2,6-dimethyl-1,4-phenyleneether). In contrast, prior art poly(2,6-dimethyl-1,4-phenylene ether)resins tend to exhibit a strong bias toward incorporation of terminalmorpholine residues into lower molecular weightpoly(2,6-dimethyl-1,4-phenylene ether). Again, this has practicalsignificance in that the present poly(2,6-dimethyl-1,4-phenylene ether)exhibits increased molecular weight build during compounding andimproved compatibilization with polyamides. The dependence of terminalmorpholine incorporation on molecular weight is objectivelycharacterized by separating the purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether) by molecular weight into sixequal poly(2,6-dimethyl-1,4-phenylene ether) weight fractions andcalculating the ratio of the terminal morpholine content of the sixth,lowest molecular weight fraction to the terminal morpholine content ofthe first, highest molecular weight fraction. Specifically, afterseparating the purified poly(2,6-dimethyl-1,4-phenylene ether) into sixfractions of equal poly(2,6-dimethyl-1,4-phenylene ether) weight contentand decreasing molecular weight, the ratio of the sixth, lowestmolecular weight fraction mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group to the first, highest molecularweight fraction mole percent of poly(2,6-dimethyl-1,4-phenylene ether)comprising a terminal morpholine-substituted phenoxy group is less thanor equal to 4, specifically 1 to 4, more specifically 1 to 3, still morespecifically 1 to 2.

In some embodiments, the first, highest molecular weight fractioncomprises wherein 10 to 40 mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group; and the purified sample of thepoly(2,6-dimethyl-1,4-phenylene ether) comprises 0.1 to 2.2 weightpercent of poly(2,6-dimethyl-1,4-phenylene ether) having a molecularweight more than fifteen times greater than the number average molecularweight of the entire purified sample as a whole.

The invention includes methods of preparing thepoly(2,6-dimethyl-1,4-phenylene ether) described herein. For example,one embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture during the course of the polymerization (i.e., thereaction is conducted in semi-batch mode, at least with regard toaddition of 2,6-dimethylphenol, as contrasted with a batch reaction inwhich all of the 2,6-dimethylphenol is present in the reaction at theinitiation of polymerization); contacting the product mixture with anaqueous chelant solution, thereby inducing a liquid-liquid phaseseparation that yields a chelation mixture comprising solidpoly(2,6-dimethyl-1,4-phenylene ether), an aqueous phase comprisingchelated copper, and an organic phase comprising oligomericpoly(2,6-dimethyl-1,4-phenylene ether); separating the solidpoly(2,6-dimethyl-1,4-phenylene ether) from the chelation mixture; andrecycling to the reactor at least a portion of the organic phasecomprising oligomeric poly(2,6-dimethyl-1,4-phenylene ether). Theoligomeric poly(2,6-dimethyl-1,4-phenylene ether) is defined herein ascomprising 2,6-dimethyl-1,4-phenylene ether repeat units and having anumber average molecular weight of 250 to 6,000 atomic mass units. Insome cases, the oligomeric poly(2,6-dimethyl-1,4-phenylene ether)comprises a polymerization catalyst moiety (in which case it is “living”oligomer). In other cases, the oligomericpoly(2,6-dimethyl-1,4-phenylene ether) is essentially free ofpolymerization catalyst moiety (in which case it is “dead” oligomer).Although the method described above includes an oligomer recycling step,the poly(2,6-dimethyl-1,4-phenylene ether) can also be synthesizedwithout recycling oligomeric poly(2,6-dimethyl-1,4-phenylene ether) tothe reactor. Specific procedures for synthesizing and isolating thepoly(2,6-dimethyl-1,4-phenylene ether) are described in the workingexamples below.

Another embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising a solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture during the course of the polymerization, andwherein the reaction mixture prior to initiating polymerizing the2,6-dimethylphenol comprises 0.05 to 15 parts by weight of oligomericpoly(2,6-dimethyl-1,4-phenylene ether) per 100 parts by weight of thesolvent for the poly(2,6-dimethyl-1,4-phenylene ether). In thisembodiment, the oligomeric poly(2,6-dimethyl-1,4-phenylene ether) istypically present in a recycled solvent comprising 0.05 to 15 weightpercent of oligomeric poly(2,6-dimethyl-1,4-phenylene ether), based onthe total weight of recycled solvent.

Another embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising a solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture during the course of the polymerization; andwherein reaction mixture prior to initiating polymerizing the2,6-dimethylphenol comprises 0.05 to 15 parts by weight percent ofdissolved oligomeric poly(2,6-dimethyl-1,4-phenylene ether) per 100parts by weight of the solvent for the poly(2,6-dimethyl-1,4-phenyleneether). In this embodiment, the dissolved oligomericpoly(2,6-dimethyl-1,4-phenylene ether) is typically present in arecycled solvent comprising 0.05 to 15 weight percent of oligomericpoly(2,6-dimethyl-1,4-phenylene ether), based on the total weight ofrecycled solvent.

Another embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising a solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture during the course of the polymerization; whereinthe reaction mixture prior to initiating polymerizing the2,6-dimethylphenol comprises 0.05 to 15 parts by weight of dissolvedoligomeric poly(2,6-dimethyl-1,4-phenylene ether) per 100 parts byweight of the solvent for the poly(2,6-dimethyl-1,4-phenylene ether);and wherein the oligomeric poly(2,6-dimethyl-1,4-phenylene ether) isessentially free of polymerization catalyst moiety. In this context,“essentially free” means that the oligomericpoly(2,6-dimethyl-1,4-phenylene ether) does not comprise polymerizationcatalyst moiety in an amount effective to induce polymerization.Typically, the oligomeric poly(2,6-dimethyl-1,4-phenylene ether)comprises polymerization catalyst moiety in an amount less than 2 partsper thousand by weight, specifically less than or equal to 1 part perthousand by weight, based on the weight of the oligomericpoly(2,6-dimethyl-1,4-phenylene ether).

Another embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture during the course of the polymerization; whereinthe reaction mixture prior to initiating polymerizing the2,6-dimethylphenol comprises 0.05 to 15 parts by weight of dissolvedoligomeric poly(2,6-dimethyl-1,4-phenylene ether) per 100 parts byweight of the solvent for the poly(2,6-dimethyl-1,4-phenylene ether);wherein the oligomeric poly(2,6-dimethyl-1,4-phenylene ether) isessentially free of polymerization catalyst moiety; and wherein thedissolved oligomeric poly(2,6-dimethyl-1,4-phenylene ether) has a numberaverage molecular weight less than 4000 atomic mass units. In thiscontext, “essentially free” means that the oligomericpoly(2,6-dimethyl-1,4-phenylene ether) does not comprise polymerizationcatalyst moiety in an amount effective to induce polymerization.Typically, the oligomeric poly(2,6-dimethyl-1,4-phenylene ether)comprises polymerization catalyst moiety in an amount less than 2 partsper thousand by weight, specifically less than or equal to 1 part perthousand by weight, based on the weight of the oligomericpoly(2,6-dimethyl-1,4-phenylene ether).

Another embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture in a substantially pure (e.g., at least 98 weightpercent pure) molten state during the course of the polymerization; andwherein the reaction mixture prior to initiating polymerizing the2,6-dimethylphenol comprises 0.05 to 15 parts by weight of dissolvedoligomeric poly(2,6-dimethyl-1,4-phenylene ether) per 100 parts byweight of the solvent for the poly(2,6-dimethyl-1,4-phenylene ether).

Another embodiment is a method of preparing apoly(2,6-dimethyl-1,4-phenylene ether), comprising: polymerizing2,6-dimethylphenol in a reaction mixture to form a product mixturecomprising solid poly(2,6-dimethyl-1,4-phenylene ether); wherein thereaction mixture comprises the 2,6-dimethylphenol, a catalyst comprisingcopper and morpholine, a solvent for the poly(2,6-dimethyl-1,4-phenyleneether), and a non-solvent for the poly(2,6-dimethyl-1,4-phenyleneether); wherein at least a portion of the 2,6-dimethylphenol is added tothe reaction mixture in a substantially pure (e.g., at least 98 weightpercent pure) molten state during the course of the polymerization;wherein the reaction mixture prior to initiating polymerizing the2,6-dimethylphenol comprises 0.05 to 15 parts by weight of dissolvedoligomeric poly(2,6-dimethyl-1,4-phenylene ether) per 100 parts byweight of the solvent for the poly(2,6-dimethyl-1,4-phenylene ether);wherein the oligomeric poly(2,6-dimethyl-1,4-phenylene ether) isessentially free of polymerization catalyst moiety; and wherein thedissolved oligomeric poly(2,6-dimethyl-1,4-phenylene ether) has a numberaverage molecular weight of 250 to 4000 atomic mass units. In thiscontext, “essentially free” means that the oligomericpoly(2,6-dimethyl-1,4-phenylene ether) does not comprise polymerizationcatalyst moiety in an amount effective to induce polymerization.Typically, the oligomeric poly(2,6-dimethyl-1,4-phenylene ether)comprises polymerization catalyst moiety in an amount less than 2 partsper thousand by weight, specifically less than or equal to 1 part perthousand by weight, based on the weight of the oligomericpoly(2,6-dimethyl-1,4-phenylene ether).

In all of the above embodiments in which the reaction mixture prior toinitiating polymerizing the 2,6-dimethylphenol comprises 0.05 to 15parts by weight of oligomeric poly(2,6-dimethyl-1,4-phenylene ether) per100 parts by weight of the solvent for thepoly(2,6-dimethyl-1,4-phenylene ether, the amount of the oligomericpoly(2,6-dimethyl-1,4-phenylene ether) can be specifically 0.05 to 10parts by weight, more specifically 0.05 to 5 parts by weight.

The current inventors unexpectedly found that the presence of oligomericpoly(2,6-dimethyl-1,4-phenylene ether) in the reaction mixture prior toinitiation polymerization did not result in the formation of a highmolecular weight shoulder in the molecular weight distribution of theproduct poly(2,6-dimethyl-1,4-phenylene ether). While not wishing to bebound by any particular theory, the present inventors speculate that thehigh molecular weight shoulder present in the Comparative Example 4 ofthe working examples below may be due to recycling to the reactor of“living” oligomer, that is, oligomer to which copper catalyst is stillbound. This living oligomer can then further polymerize to form afraction of poly(2,6-dimethyl-1,4-phenylene ether) with exceptionallyhigh molecular weight compared to poly(2,6-dimethyl-1,4-phenylene ether)synthesized from 2,6-dimethylphenol alone (i.e., without living oligomerinitially present). By contacting the full product mixture—not just thesolid poly(2,6-dimethyl-1,4-phenylene ether)—with the aqueous chelantsolution, the present method avoids the formation of the very highmolecular weight fraction that detracts from performance in applicationssuch as extrusion molding.

The invention includes at least the following embodiments.

Embodiment 1

A poly(2,6-dimethyl-1,4-phenylene ether), wherein a purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether) prepared by dissolution of thepoly(2,6-dimethyl-1,4-phenylene ether) in toluene, precipitation frommethanol, reslurry, and isolation has a monomodal molecular weightdistribution in the molecular weight range of 250 to 1,000,000 atomicmass units, and comprises less than or equal to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times the number average molecular weight of the entirepurified sample; wherein the purified sample after separation into sixequal poly(2,6-dimethyl-1,4-phenylene ether) weight fractions ofdecreasing molecular weight comprises a first, highest molecular weightfraction; and wherein the first, highest molecular weight fractioncomprises at least 10 mole percent of poly(2,6-dimethyl-1,4-phenyleneether) comprising a terminal morpholine-substituted phenoxy group.

Embodiment 2

The poly(2,6-dimethyl-1,4-phenylene ether) of embodiment 1, wherein thepurified sample comprises less or equal to 2.4 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight greaterthan seven times the peak molecular weight of the entire purifiedsample.

Embodiment 3

The poly(2,6-dimethyl-1,4-phenylene ether) of embodiment 1 or 2, whereinthe purified sample comprises less than or equal to 3.2 weight percentof poly(2,6-dimethyl-1,4-phenylene ether) having a molecular weightgreater than five times the peak molecular weight of the entire purifiedsample.

Embodiment 4

The poly(2,6-dimethyl-1,4-phenylene ether) of any of embodiments 1-3,wherein the first, highest molecular weight fraction comprises 10 to 40mole percent of poly(2,6-dimethyl-1,4-phenylene ether) comprising aterminal morpholine-substituted phenoxy group.

Embodiment 5

The poly(2,6-dimethyl-1,4-phenylene ether) of any of embodiments 1-4,wherein the purified sample comprises 0.1 to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times greater than the number average molecular weight ofthe entire purified sample.

Embodiment 6

The poly(2,6-dimethyl-1,4-phenylene ether) of any of embodiments 1-3,wherein the first, highest molecular weight fraction comprises 10 to 40mole percent of poly(2,6-dimethyl-1,4-phenylene ether) comprising aterminal morpholine-substituted phenoxy group; and wherein the purifiedsample comprises 0.1 to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times greater than the number average molecular weight ofthe entire purified sample.

Embodiment 7

The poly(2,6-dimethyl-1,4-phenylene ether) of embodiment 1, wherein thepurified sample after separation into six equalpoly(2,6-dimethyl-1,4-phenylene ether) weight fractions of decreasingmolecular weight comprises a first, highest molecular weight fractioncharacterized by a first fraction mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group, and a sixth, lowest molecularweight fraction characterized by a sixth fraction mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group, and wherein a ratio of the sixthfraction mole percent of poly(2,6-dimethyl-1,4-phenylene ether)comprising a terminal morpholine-substituted phenoxy group to the firstfraction mole percent of poly(2,6-dimethyl-1,4-phenylene ether)comprising a terminal morpholine-substituted phenoxy group is less thanor equal to 4.

The invention is further illustrated by the following non-limitingexamples.

Comparative Example 1

This comparative example describes the batch synthesis ofpoly(2,6-dimethyl-1,4-phenylene ether) in a mixture of a solvent for thepoly(2,6-dimethyl-1,4-phenylene ether) (toluene) and a nonsolvent forthe poly(2,6-dimethyl-1,4-phenylene ether) (methanol). Thepolymerization catalyst was prepared from a copper salt (CuCl₂2H₂O) anda secondary amine(morpholine). The end-of-reaction mixture was a slurrythat was treated with citric acid to chelate the copper ion. Otherchelants known in the art can also be used, includingethylenediaminetetracetic acid and its salts, and nitrilotriacetic acidand its salts.

The polymerization was conducted on a laboratory scale. The apparatusconsisted of a bubbling reactor (Mettler Toledo RC1 e reactor, Type 3,1.8 liter, 100 bar) equipped with a stirrer, temperature control system,nitrogen padding, oxygen bubbling tube, and computerized control system(including two RD10 controllers). There were also two separate feedingports and pumps for dosing reactants into the reactor. The test batchesrunning conditions for Examples 1-3 and Comparative Examples 1-3 aresummarized in Table 1. The raw materials used are summarized in Table 2.

TABLE 1 C. Ex. 1 Ex. 1 C. Ex. 2 C. Ex. 3 Ex. 2 Ex. 3 Feed Batch Semi-Batch Batch Semi- Semi- batch batch batch Oligomers No No Yes Yes No YesReaction time, min 55 55 55 40 45 45 Temperature, C. 40 40 40 40 40 40Toluene, g 312.03 312.03 312.03 312.03 312.03 312.03 Nitrogen, sccm 12201220 1220 1220 1220 1220 Oxygen, sccm 500 500 500 500 500 500 Mol O/molMonomer NA* 1.01 NA NA 1.01 1.01 fed Morpholine, g 68.01 68.01 68.0168.01 68.01 68.01 Catalyst: CuCl₂•2H₂O, g 1.12 1.12 1.12 1.12 1.12 1.12Methanol, g 1.13 1.13 1.13 1.13 1.13 1.13 Methanol, g 307.43 307.43307.43 307.43 307.43 307.43 Monomer: 2,6-dimethylphenol, g 187.67 187.67187.67 187.67 187.67 187.67 Toluene, g 187.67 187.67 187.67 187.67187.67 187.67 PPE Oligomers, wt % of 0 0 1 1 0 1 total Toluene *NA = notapplicable (all monomer initially present)

TABLE 2 Raw Material CAS Reg. No. Source 2,6-dimethylphenol 576-26-1SABIC Innovative Plastics Morpholine 110-91-8 Fisher ScientificCuCl2•2H2O 10125-13-0 Fisher Scientific Toluene 108-88-3 Sunoco Methanol67-56-1 SABIC Americas Citric acid 77-92-9 International Chemical Inc.PPE Oligomer 25134-01-4 SABIC Innovative Plastics

The reactor was loaded with 312.03 grams of toluene and the contentswere stirred under nitrogen atmosphere. The temperature was maintainedat 40° C. Morpholine (68.01 grams) was added to the reactor and mixedfor 5 minutes, followed by addition of a cupric chloride solution inmethanol. The cupric chloride solution was prepared by mixing 1.12 gramsCuCl₂2H₂O with 1.13 grams methanol with addition of this mixture to307.43 grams methanol. After mixing the above-mentioned components for 5minutes, 375.33 grams of a 50% solution of 2,6-dimethylphenol in toluenewas added. Oxygen gas was bubbled into the reactor to carry out thepolymerization. Oxygen flow was maintained for 55 minutes, at whichpoint the oxygen flow was stopped and the reactor contents weretransferred to a vessel containing 2.5 grams citric acid in 3.8 gramsmethanol. The solution was stirred at 45° C. for 45 minutes and theliquid phase was removed by filtration. The remaining wet cake waswashed (rinsed) with a solution of 64 grams toluene and 168 gramsmethanol at ambient temperature (defined as 23±3° C.), and filteredagain. The wet cake was washed (rinsed) with 319 grams methanol atsimilar ambient temperature, filtered, and dried in a vacuum oven at110° C. to obtain dry powder (“isolated poly(2,6-dimethyl-1,4-phenyleneether)”). The characterization of this sample is summarized in Table 3.

The isolated poly(2,6-dimethyl-1,4-phenylene ether) was further purifiedto form a purified sample as follows. The isolatedpoly(2,6-dimethyl-1,4-phenylene ether) was dissolved in toluene atambient temperature at 25 weight percent solids to form apoly(2,6-dimethyl-1,4-phenylene ether) solution. Thepoly(2,6-dimethyl-1,4-phenylene ether) was precipitated by adding 1weight part of the poly(2,6-dimethyl-1,4-phenylene ether) solution atambient temperature to 2 weight parts of methanol at ambienttemperature, filtering the wet cake, reslurrying the wetcake in methanol(again, using 2 weight parts of methanol at ambient temperature),filtering again, and drying in a vacuum oven for 1 hour at 110° C. toobtain a purified sample of poly(2,6-dimethyl-1,4-phenylene ether).Characterization of the purified sample is summarized in Table 4.

Example 1

The method of Comparative Example 1 was repeated, except that the 50%solution of 2,6-dimethylphenol in toluene was not added to the bubblingreactor before oxygen gas addition, but was instead fed to the reactorat a rate of 10.7 grams/minute concurrently with the oxygen addition.This gradual addition of monomer during the course of polymerization isthe process characteristic summarized as “semi-batch” in the Table 1 rowlabeled “Feed”. In contrast, this aspect of Comparative Example 1 ischaracterized as “batch” because all 2,6-dimethylphenol was present whenthe polymerization was initiated with introduction of oxygen gas.

Comparative Example 2

The method of Comparative Example 1 was repeated with two exceptions.The first exception was that the material added to the bubbling reactorbefore the start of oxygen gas addition also contained 5 grams ofpoly(2,6-dimethyl-1,4-phenylene ether) oligomer. This oligomer wasderived from the liquid phase of a previous polymerization, and it is a“dead” oligomer in the sense that the entire polymerization productmixture was subjected to chelation to remove copper ion. In other words,the poly(2,6-dimethyl-1,4-phenylene ether) oligomer was essentially freeof polymerization catalyst moiety. The number average molecular weightof the oligomer, as measured by GPC against polystyrene standards, was886 atomic mass units, and the weight average molecular weight was 1873atomic mass units. The second exception was that at the end of the 45minutes of mixing at 45° C. after adding citric acid solution, theliquid phase of reaction mixture was removed by filtration. Theremaining wet cake was reslurried (not just rinsed) with a solution of64 grams toluene and 168 grams methanol at ambient temperature andfiltered again. The obtained wet cake was reslurried again (not rinsed)with 319 grams methanol at ambient temperature, filtered, and dried in avacuum oven at 110° C. to obtain dry powder. The characterization ofthis sample is summarized in Table 3. The product was further purifiedby dissolving the dry powder in toluene at 25 weight percent solids,precipitating by mixing in 2 weight parts of methanol per 1 weight partof the 25 weight percent solution at ambient temperature, filtering thewet cake, reslurrying the wetcake in methanol (again, with 2 weightparts of methanol), filtering again, and drying in a vacuum oven for 1hour at 110° C. to obtain a purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether). The characterization of thepurified sample is summarized in Table 4.

Comparative Example 3

The method of Comparative Example 2 was repeated, except that the totalreaction time (oxygen addition time) was decreased from 55 minutes to 40minutes.

Example 2

The method of Example 1 was repeated with two exceptions. The firstexception was that the total reaction time (oxygen addition time) wasdecreased from 55 minutes to 45 minutes. The second exception was thatat the end of the 45 minutes of mixing at 45° C. after adding citricacid solution, the liquid phase of the reaction mixture was removed byfiltration. The remaining wet cake was reslurried (not just rinsed) witha solution of 64 grams toluene and 168 grams methanol at ambienttemperature, and filtered again. The obtained wet cake was reslurriedagain (not rinsed) with 319 grams methanol at ambient temperature,filtered, and dried in a vacuum oven at 110° C. to obtain a dry powder(isolated poly(2,6-dimethyl-1,4-phenylene ether). The characterizationof the isolated poly(2,6-dimethyl-1,4-phenylene ether) is summarized inTable 3.

The isolated poly(2,6-dimethyl-1,4-phenylene ether) was further purifiedby dissolving the dry powder in toluene at 25 weight percent solids,precipitating by mixing in 2 weight parts of methanol per 1 weight partof the 25 weight percent solution at ambient temperature, filtering thewet cake, reslurrying the wetcake in methanol (again, with 2 weightparts methanol), filtering again, and drying in a vacuum oven for 1 hourat 110° C. to obtain a purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether). The characterization of thepurified sample is summarized in Table 4.

Example 3

The method of Example 2 was repeated, except that all toluene solutions(i.e., the initial toluene charge and the 2,6-dimethylphenol solution)added to the bubbling reactor also contained 1% by weight, based ontotal toluene, of the poly(2,6-dimethyl-1,4-phenylene ether) oligomerdescribed in Comparative Example 2.

Comparative Example 4

Comparative Example 4 is a poly(2,6-dimethyl-1,4-phenylene ether)obtained in China as grade LXR040 from Bluestar New Chemical MaterialsCo., Ruicheng Branch, China. This commercial sample was first analyzedas received and its characterization is summarized in Table 3. Thecommercially-obtained powder sample was further purified to form apurified sample by dissolving the dry powder in toluene at 25 weightpercent solids, precipitating by mixing in 2 weight parts of methanolwith 1 weight part of the 25 weight percent solution at ambienttemperature, filtering the wet cake, reslurrying the wetcake in methanol(again, with 2 weight parts methanol), filtering again, and drying in avacuum oven for 1 hour at 110° C. to obtain a purified sample ofpoly(2,6-dimethyl-1,4-phenylene ether). The characterization of thepurified sample is summarized in Table 4.

Product Analysis

For each of the poly(2,6-dimethyl-1,4-phenylene ether) resins associatedwith the working examples above, intrinsic viscosity was determined byUbbelohde-type viscometer at 25° C. Molecular weight was determined bygel permeation chromatography (GPC) relative to polystyrene standardsusing UV detection at 280 nanometers wavelength. Molecular structure wasdetermined by proton nuclear magnetic resonance spectroscopy (¹H NMR).The results are summarized in Tables 3 and 4. The molecular weightdistribution for the purified sample derived from thepoly(2,6-dimethyl-1,4-phenylene ether) prepared according to Example 2is shown in FIG. 1. The molecular weight distribution for the purifiedsample derived from the poly(2,6-dimethyl-1,4-phenylene ether) preparedof Comparative Example 4 is shown in FIG. 2. Table 3 lists data for thedry powders obtained after the first two washes of Examples 1-3 andComparative Examples 1-3, and for the Comparative Example 4 sample asreceived (that is, data in this table is for the respectivepoly(2,6-dimethyl-1,4-phenylene ether) resins before they wereredissolved/reprecipitated/reslurried/isolated). Table 4 lists data forthe purified samples. In the tables, “IV” signifies intrinsic viscosityin units of deciliters per gram (dL/g); “M_(n)” signifies number averagemolecular weight in units of atomic mass units (AMU); “M_(w),” signifiesweight average molecular weight in units of AMU; “D (M_(w)/M_(n))”signifies the polydispersity, which is the ratio of weight averagemolecular weight to number average molecular weight; “M_(p)” signifiesthe peak molecular weight, which is the molecular weight at the peak ofthe GPC chromatogram in units of AMU; “%<500K” signifies the weightpercent of the total sample that has molecular weight less than 500,000AMU; “M_(w)/M_(p)” signifies the ratio of weight average molecularweight to peak molecular weight; “M_(p)/M_(n)” signifies the ratio ofpeak molecular weight to number average molecular weight; “Monomodalfrom 250 to 1,000,000 AMU?” signifies whether the molecular weightdistribution from 250 to 1,000,000 AMU is monomodal (i.e., whether theplot of molar mass (x-axis) versus UV light absorbance (“W(log M)”;(y-axis) has one and only one maximum point with a slope of zero); “FracM_(n)/Bulk M_(n)” signifies, for a given fraction, the ratio of thefraction's number average molecular weight to the whole sample's numberaverage molecular weight; “Frac M_(w)/Bulk M_(w)” signifies, for a givenfraction, the ratio of the fraction's weight average molecular weight tothe whole sample's weight average molecular weight; “wt % MW≧15×M_(n)”signifies the weight percent of the whole sample or fraction (dependingon the row in Table 4) having a molecular weight greater than 15 timesthe number average molecular weight of the whole sample; “wt %MW≧5×M_(p)” signifies the weight percent of the whole sample or fractionhaving a molecular weight greater than five times the peak molecularweight of the whole sample; “wt % MW≧7×M_(p)” signifies the weightpercent of the whole sample or fraction having a molecular weightgreater than seven times the peak molecular weight of the whole sample.Data in the remaining columns of Table 4 was obtained by NMR: “wt %Term. Morph” signifies weight of bound morpholine in thehydroxide-functionalized end of the poly(2,6-dimethyl-1,4-phenyleneether), expressed as weight percent of morpholino (C₄H₈NO) groupsrelative to the total weight of the poly(2,6-dimethyl-1,4-phenyleneether); “mol % Int. Morph” signifies the moles of internally-boundmorpholino groups relative to the moles ofpoly(2,6-dimethyl-1,4-phenylene ether) chains; “mol % Term. Morph”signifies the moles of bound morpholine units in thehydroxide-functionalized end of the poly(2,6-dimethyl-1,4-phenyleneether) molecule relative to the moles of poly(2,6-dimethyl-1,4-phenyleneether) chains; “mol % Int. Biph” signifies the moles of internally bound2,2′,6,6′-tetramethyl-4,4′-biphenoxy units as percent of moles ofpoly(2,6-dimethyl-1,4-phenylene ether) chains; “Term./Int. Morph”signifies “mol % Term. Morph” divided by “mol % Int. Morph”;“Term6/Term1” signifies the “mol % Term. Morph” for fraction 6 dividedby the mol % Term. Morph” for fraction 1 of the same sample. “Mono”signifies whether the molecular weight distribution from 250 to1,000,000 atomic mass units is monomodal.

The values of weight %, absolute molecular weight, and mol % obtainedfrom ¹H NMR were calculated as described in the equations below. Theproton peak integrals on which the calculations are based are shown inthe chemical structures below. Internal morpholine is based on the peakat 3.36 ppm for 2 protons (P1); terminal morpholine is based on the peakat 3.74 ppm for 4 protons (P2); internal biphenyl is based on the peakat 7.35 ppm for 4 protons (P3); PPE tail is based on the peak at 7.09ppm for 3 protons (P4); PPE-OH head is based on the peak at 6.36 ppm for2 protons (P5); and PPE repeat unit is based on the peak at 6.46 ppm for2 protons (P6). Molecular weight values used in the calculations were 86for internal and terminal morpholine (C₄H₈NO), 240 for2,2′,6,6′-tetramethyl-4,4′-biphenoxy(C₁₆H₁₆O₂), and 120 for PPE tail(C₈H₉O).

A general equation for calculating the weight percent of a functionalgroup is given below as equation (1).

$\begin{matrix}{{\frac{\begin{matrix}{Moiety} \\{{Peak}\mspace{14mu} {Integral}}\end{matrix}}{\begin{matrix}{{PPE}\mspace{14mu} {Repeat}} \\{{Unit}\mspace{14mu} {Integral}}\end{matrix}} \times \frac{\begin{matrix}{{Mw}\mspace{14mu} {Moiety}} \\\left( {{see}\mspace{14mu} {text}} \right)\end{matrix}}{\begin{matrix}{{Mw}\mspace{14mu} {PPE}} \\{{Repeat}\mspace{14mu} {Unit}} \\(120)\end{matrix}} \times \frac{\begin{matrix}\begin{matrix}{Number} \\{Equivalent}\end{matrix} \\{{Protons}\mspace{14mu} {{PPE}(2)}}\end{matrix}}{\begin{matrix}\begin{matrix}{Number} \\{Equivalent} \\{{Protons}\mspace{14mu} {Moiety}}\end{matrix} \\\left( {{see}\mspace{14mu} {text}} \right)\end{matrix}} \times 100} = \begin{matrix}{{Wt}.\mspace{14mu} \%} \\{Moiety} \\\left( {{to}\mspace{14mu} {PPE}} \right)\end{matrix}} & (1)\end{matrix}$

An equation for calculating polymer molecular weight based on NMRintegrals for internal and terminal groups is given below as equation(2).

$\begin{matrix}{{\frac{\begin{pmatrix}\begin{matrix}{\left( {\frac{{Int}\mspace{14mu} {Biph}\mspace{14mu} {Integral}}{4}*2} \right) +} \\{\left( \frac{{Int}\mspace{14mu} {Morph}\mspace{14mu} {Integral}}{2} \right) +}\end{matrix} \\\left( \frac{{PPE}\mspace{14mu} {rep}\mspace{14mu} {unit}\mspace{14mu} {Integral}}{2} \right)\end{pmatrix}}{\begin{matrix}{{\begin{pmatrix}\begin{matrix}{\left( {\left( {{PPE} - {{OH}\mspace{14mu} {Integral}}} \right)/2} \right) +} \\{\left( {{Ext}\mspace{14mu} {Morph}\mspace{14mu} {{Integral}/4}} \right) -}\end{matrix} \\\left( {{PPE}\mspace{14mu} {Tail}\mspace{14mu} {{Integral}/3}} \right)\end{pmatrix}*0.5} +} \\\left( {{PPE}\mspace{14mu} {Tail}\mspace{14mu} {{Integral}/3}} \right)\end{matrix}} \times 120} = \begin{matrix}{Absoute} \\{Molecular} \\{Weight}\end{matrix}} & (2)\end{matrix}$

An equation for calculating the mole percent of a functional group isgiven below as equation (3).

$\begin{matrix}{{\frac{\begin{matrix}{Moiety} \\{{Peak}\mspace{14mu} {Integral}}\end{matrix}}{\begin{matrix}{{PPE}\mspace{14mu} {Repeat}} \\{{Unit}\mspace{14mu} {Integral}}\end{matrix}} \times \frac{\begin{matrix}{Number} \\\begin{matrix}{Equivalent} \\{{Protons}\mspace{14mu} {{PPE}(2)}}\end{matrix}\end{matrix}}{\begin{matrix}{Number} \\{Equivalent} \\{{Protons}\mspace{14mu} {Moiety}} \\\left( {{see}\mspace{14mu} {text}} \right)\end{matrix}} \times \frac{\begin{matrix}{Absolute} \\{Molecular} \\{Weight}\end{matrix}}{120} \times 100} = \begin{matrix}{{Mol}.\mspace{14mu} \%} \\{Moiety} \\\left( {{to}\mspace{14mu} {PPE}} \right)\end{matrix}} & (3)\end{matrix}$

TABLE 3 % < Mw/ Mp/ IV M_(n) M_(w) D (M_(w)/M_(n)) M_(p) 500K Mp Mn MonoC. Ex. 1 0.722 29624 131530 4.44 63505 96.15 2.07 2.14 yes Ex. 1 0.61828790 90790 3.15 61632 99.26 1.47 2.14 yes C. Ex. 2 0.593 22639 1159905.12 55824 96.76 2.08 2.47 yes C. Ex. 3 0.177 5829 26292 4.51 9556 99.842.75 1.64 yes Ex. 2 0.412 23970 55573 2.32 41178 99.89 1.35 1.72 yes Ex.3 0.416 24897 63477 2.55 39905 99.46 1.59 1.60 yes C. Ex. 4 0.361 1687055369 3.28 33686 98.58 1.64 2.00 no

For characterization of the composition as a function of molecularweight fraction, fractions from six gel permeation chromatographyinjections (36 mg of total material injected) were collected using aGilson fraction collector. The effluent eluting between 9 and 23 minutesrun time was divided over 60 test tubes which were later recombined togive 6 fractions with each containing approximately 16.67% of the totalpoly(2,6-dimethyl-1,4-phenylene ether), as determined from area percentof the chromatogram. After evaporation of the fractions to approximately15 milliliters under nitrogen flow, a small part (200 microliters) ofthe six fractions was analyzed by gel permeation chromatography toconfirm the success of the fractionation. The remaining part was usedfor ¹H NMR analysis. The portion used for NMR analysis was evaporated todryness at 50° C. under a nitrogen flow. One milliliter of deuteratedchloroform (with tetramethylsilane as internal standard) was added andthe samples were analyzed by ¹H NMR (512 scans). The results arepresented in Table 4.

TABLE 4 Frac Frac M_(n)/ M_(w)/ wt % wt % wt % wt % Mol % Mol % Mol %Term./ Term Bulk Bulk MW ≧ MW ≧ MW ≧ Term. Int. Term. Int. Int. 6/ M_(n)M_(w) M_(p) Mono M_(n) M_(w) 15 × M_(n) 5 × M_(p) 7 × M_(p) Morph MorphMorph Biph Morph Term 1 C. Ex. 1 Whole 30500 105500 54900 Yes 1.00 1.004.2 7.4 4.2 0.33 37.4 60.6 18.4 1.62 1.23 sample Fraction 1 122700464200 302800 4.02 4.40 0.14 93.7 38.0 27.6 0.41 Fraction 2 101000180600 153400 3.31 1.71 0.17 70.1 52.0 30.4 0.74 Fraction 3 62900 10300092000 2.06 0.98 0.21 54.1 55.7 20.5 1.03 Fraction 4 39500 60200 539001.30 0.57 0.29 46.6 68.9 16.4 1.48 Fraction 5 24300 36400 30200 0.800.35 0.41 30.6 72.1 14.2 2.35 Fraction 6 7185 21000 16700 0.24 0.20 0.7817.6 46.5 12.9 2.65 Ex. 1 Whole 29900 76600 54400 Yes 1.00 1.00 1.2 2.91.1 0.28 30.9 55.9 6.6 1.81 1.99 sample Fraction 1 122300 255700 1961004.09 3.34 0.08 63.9 24.8 13.0 0.39 Fraction 2 82200 122500 111400 2.751.60 0.12 62.3 39.0 6.2 0.63 Fraction 3 56500 82700 78200 1.89 1.08 0.1854.6 56.5 11.7 1.03 Fraction 4 40200 58800 40200 1.34 0.77 0.26 38.765.8 6.7 1.70 Fraction 5 28000 41200 35400 0.94 0.54 0.35 31.3 69.1 14.82.21 Fraction 6 10200 23800 21100 0.34 0.31 0.58 17.2 49.4 6.4 2.86 C.Ex. 2 Whole 25500 86500 49200 Yes 1.00 1.00 4.0 6.6 3.6 0.36 27.3 59.515.6 2.18 2.04 sample Fraction 1 115200 391000 247200 4.52 4.52 0.1164.4 23.8 27.9 0.37 Fraction 2 90000 150800 128500 3.53 1.74 0.14 54.538.3 19.7 0.70 Fraction 3 55300 87600 76000 2.17 1.01 0.22 49.8 55.419.8 1.11 Fraction 4 35400 55900 49300 1.39 0.65 0.31 36.0 67.8 16.31.88 Fraction 5 22900 35900 30900 0.90 0.42 0.42 26.0 68.6 13.5 2.64Fraction 6 5060 17700 17500 0.20 0.20 0.88 10.4 48.7 10.9 4.67 C. Ex. 3Whole 8260 22000 12400 Yes 1.00 1.00 3.2 7.2 4.5 0.14 1.5 9.1 17.9 5.980.36 sample Fraction 1 53200 99800 64600 6.44 4.54 0.12 31.0 23.2 22.80.75 Fraction 2 25200 33000 30100 3.05 1.50 0.09 9.5 16.5 30.4 1.73Fraction 3 15400 19800 18200 1.86 0.90 0.06 2.1 7.8 29.3 3.75 Fraction 49920 13200 11900 1.20 0.60 0.07 1.5 5.7 22.7 3.66 Fraction 5 6315 92158685 0.76 0.42 0.12 1.1 6.8 18.0 5.95 Fraction 6 2395 5500 4635 0.290.25 0.31 1.0 8.3 8.7 8.59 Ex. 2 Whole 25600 48700 38500 Yes 1.00 1.000.3 2.2 0.8 0.26 10.7 50.0 0.3 4.66 1.38 sample Fraction 1 95500 153300118000 3.73 3.15 0.08 54.2 26.4 6.2 0.49 Fraction 2 59600 77800 717002.33 1.60 0.14 37.4 46.9 9.6 1.25 Fraction 3 39600 53900 51200 1.55 1.110.14 29.8 38.1 5.0 1.28 Fraction 4 29300 39100 40000 1.14 0.80 0.18 17.637.3 4.4 2.11 Fraction 5 21600 28500 27300 0.84 0.59 0.22 11.8 36.4 3.03.09 Fraction 6 7650 18500 18100 0.30 0.38 0.49 9.7 36.4 3.6 3.75 Ex. 3Whole 25400 49700 38600 Yes 1.00 1.00 0.7 2.6 1.3 0.25 17.7 50.4 0.12.85 1.12 sample Fraction 1 81000 159600 94400 3.19 3.21 0.09 57.7 29.913.3 0.52 Fraction 2 44200 63900 54300 1.74 1.29 0.12 39.1 37.6 11.30.96 Fraction 3 32000 47400 40500 1.26 0.95 0.16 25.3 37.3 7.1 1.48Fraction 4 28100 42900 47600 1.11 0.86 0.18 22.3 39.4 7.1 1.76 Fraction5 23900 34600 34700 0.94 0.70 0.20 18.8 39.1 6.0 2.08 Fraction 6 860021100 20100 0.34 0.42 0.41 12.7 33.6 6.8 2.65 C. Ex. 4 Whole 19200 5200038000 No 1.00 1.00 2.4 3.4 2.6 0.20 6.5 28.4 3.8 4.39 4.37 sampleFraction 1 79800 251200 99900 4.16 4.83 0.03 35.6 5.8 47.1 0.16 Fraction2 52600 69700 67300 2.74 1.34 0.09 19.9 29.6 5.5 1.49 Fraction 3 3740050000 49600 1.95 0.96 0.13 10.6 31.2 4.4 2.93 Fraction 4 25900 3530034500 1.35 0.68 0.19 7.3 34.1 4.7 4.67 Fraction 5 17200 24900 22200 0.900.48 0.22 3.2 27.4 2.7 8.48 Fraction 6 5210 13900 12500 0.27 0.27 0.512.0 25.4 2.3 12.84

Based on the properties in Tables 3 and 4, a least four featuresdistinguish the inventive and comparative examples. First, as indicatedin Table 4, each of the comparative examples comprises greater than 2.2weight percent of poly(2,6-dimethyl-1,4-phenylene ether) having amolecular weight more than 15 times the number average molecular weightof the sample as a whole. The practical significance of this firstdifference is that the inventive poly(2,6-dimethyl-1,4-phenylene ether)resins will exhibit reduced melt breakage in extrusion applications.Second, as indicated in Table 3, Comparative Example 4 does not have amonomodal molecular weight distribution between 250 and 1,000,000 atomicmass units. The existence of a high molecular weight shoulder in theComparative Example 4 sample also contributes to diminished performancein extrusion applications. Third, as indicated in Table 4, ComparativeExample 4 comprises a first (highest molecular weight) fraction whereinless than 10 mole percent of poly(2,6-dimethyl-1,4-phenylene ether)comprises a terminal morpholine-substituted phenoxy group. The practicalsignificance of this third difference is that thepoly(2,6-dimethyl-1,4-phenylene ether)s of the inventive process willexhibit greater molecular weight increases during compounding with othercomponents, and they will be more easily compatibilized with polyamides.Fourth, as indicated in the Table 4 column labeled “Term6/Term1”,Comparative Example 4 comprises a much higher mole percent ofmorpholine-terminated poly(2,6-dimethyl-1,4-phenylene ether) in itslowest molecular weight fraction (fraction 6) than in its highestmolecular weight fraction (fraction 1). The practical significance ofthis fourth difference is better molecular weight build duringcompounding, and better compatibilization with polyamides.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Further, it should further be noted that the terms “first,”“second,” and the like herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context (e.g., itincludes the degree of error associated with measurement of theparticular quantity).

1. A poly(2,6-dimethyl-1,4-phenylene ether), wherein a purified sampleof poly(2,6-dimethyl-1,4-phenylene ether) prepared by dissolution of thepoly(2,6-dimethyl-1,4-phenylene ether) in toluene, precipitation frommethanol, reslurry, and isolation has a monomodal molecular weightdistribution in the molecular weight range of 250 to 1,000,000 atomicmass units, and comprises less than or equal to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times the number average molecular weight of the entirepurified sample; wherein the purified sample after separation into sixequal poly(2,6-dimethyl-1,4-phenylene ether) weight fractions ofdecreasing molecular weight comprises a first, highest molecular weightfraction; and wherein the first, highest molecular weight fractioncomprises at least 10 mole percent of poly(2,6-dimethyl-1,4-phenyleneether) comprising a terminal morpholine-substituted phenoxy group. 2.The poly(2,6-dimethyl-1,4-phenylene ether) of claim 1, wherein thepurified sample comprises less or equal to 2.4 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight greaterthan seven times the peak molecular weight of the entire purifiedsample.
 3. The poly(2,6-dimethyl-1,4-phenylene ether) of claim 1,wherein the purified sample comprises less than or equal to 3.2 weightpercent of poly(2,6-dimethyl-1,4-phenylene ether) having a molecularweight greater than five times the peak molecular weight of the entirepurified sample.
 4. The poly(2,6-dimethyl-1,4-phenylene ether) of claim1, wherein the first, highest molecular weight fraction comprises 10 to40 mole percent of poly(2,6-dimethyl-1,4-phenylene ether) comprising aterminal morpholine-substituted phenoxy group.
 5. Thepoly(2,6-dimethyl-1,4-phenylene ether) of claim 1, wherein the purifiedsample comprises 0.1 to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times greater than the number average molecular weight ofthe entire purified sample.
 6. The poly(2,6-dimethyl-1,4-phenyleneether) of claim 1, wherein the first, highest molecular weight fractioncomprises 10 to 40 mole percent of poly(2,6-dimethyl-1,4-phenyleneether) comprising a terminal morpholine-substituted phenoxy group; andwherein the purified sample comprises 0.1 to 2.2 weight percent ofpoly(2,6-dimethyl-1,4-phenylene ether) having a molecular weight morethan fifteen times greater than the number average molecular weight ofthe entire purified sample.
 7. The poly(2,6-dimethyl-1,4-phenyleneether) of claim 1, wherein the purified sample after separation into sixequal poly(2,6-dimethyl-1,4-phenylene ether) weight fractions ofdecreasing molecular weight comprises a first, highest molecular weightfraction characterized by a first fraction mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group, and a sixth, lowest molecularweight fraction characterized by a sixth fraction mole percent ofpoly(2,6-dimethyl-1,4-phenylene ether) comprising a terminalmorpholine-substituted phenoxy group, and wherein a ratio of the sixthfraction mole percent of poly(2,6-dimethyl-1,4-phenylene ether)comprising a terminal morpholine-substituted phenoxy group to the firstfraction mole percent of poly(2,6-dimethyl-1,4-phenylene ether)comprising a terminal morpholine-substituted phenoxy group is less thanor equal to 4.